The present invention relates to a process cartridge and an electrophotographic image forming apparatus.
An electrophotographic image forming apparatus is an apparatus which forms an image on recording medium with the use of an electrophotographic image formation method. As for the examples of an electrophotographic image forming apparatus, an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, or the like), a facsimile machine, a word processor, or the like, are included.
A process cartridge is a cartridge in which a charging means, a developing means or cleaning means, and an electrophotographic photoconductive drum, are integrally disposed, and which is removably mountable in the main assembly of an electrophotographic image forming apparatus. It also is a cartridge in which at least one means among a charging means, a developing means, and a cleaning means, and an electrophotographic photoconductive drum, are integrally disposed, and which is removably mountable in the main assembly of an electrophotographic image forming apparatus, or a cartridge in which a minimum of a developing means, and an electrophotographic photoconductive member, are integrally disposed, and which is removably mountable in the main assembly of an electrophotographic image forming apparatus.
An electrophotographic image forming apparatus, which employs an electrophotographic image formation process, also employs a process cartridge system, in which an electrophotographic photoconductive member, and a single, or a plurality of, processing means, which act on the electrophotographic photoconductive drum, are integrally disposed in a cartridge which is removably mountable in the main assembly of an electrophotographic image forming apparatus. This system enables a user to maintain the apparatus without relying on service personnel, drastically improving operational efficiency. Thus, a process cartridge system is widely in use in the field of an electrophotographic image forming apparatus.
In the case of an electrophotographic image forming apparatus employing a process cartridge system, a user him/herself replaces a cartridge. Therefore, some of the electrophotographic image forming apparatuses are equipped with a developer amount detecting means for informing the user of the remaining amount of the developer. As for a developer amount detecting means, there is a method in which a plurality of electrodes are disposed within a process cartridge, and the changes in the electrostatic capacity among the electrodes are detected to estimate the remaining amount of the developer.
According to a process cartridge system, as a cartridge is inserted into the apparatus main assembly, an electrical connection must be established between the cartridge and apparatus main assembly. Therefore, a cartridge is provided with electrical contacts (for example, U.S. Pat. No. 6,272,299).
According to U.S. Pat. No. 6,272,299, the electrical contacts are optimally positioned to reduce in size a process cartridge and an electrophotographic image forming apparatus.
The present invention is a result of the further development of the aforementioned prior arts regarding the positioning of the electrical contacts of a process cartridge and an electrophotographic image forming apparatus.
The primary object of the present invention is to provide a smaller process cartridge which contains input and output electrical contacts which make it possible for the remaining amount of the developer to be continually detected by the image forming apparatus main assembly side, and an electrophotographic image forming apparatus in which such a process cartridge can be removably mounted.
Another object of the present invention is to provide a smaller process cartridge, which contains input and output electrical contacts which make it possible for the remaining amount of the developer to be continually detected by the image forming apparatus main assembly side, and in which the input and output electrical contacts are positioned at one of the lengthwise ends of the process cartridge to improve the accuracy with which the remaining amount of the developer is detected by the image forming apparatus main assembly side, and an electrophotographic image forming apparatus in which such a process cartridge can be removably mounted.
Another object of the present invention is to provide a smaller process cartridge, the size of which is realized by optimally positioning the electrical contacts, inclusive of both input and output electrical contacts, and an electrophotographic image forming apparatus in which such a process cartridge can be removably mountable.
Another object of the present invention is to provide a process cartridge in which various electrodes thereof are disposed at one end of the process cartridge in terms of the lengthwise direction of the electrophotographic photoconductive member to make it possible to reduce the size of the high voltage circuit on the image forming apparatus main assembly side, and an electrophotographic image forming apparatus in which such a process cartridge can be removably mounted.
According to an aspect of the present invention, there is provided a process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus comprising an electrophotographic photosensitive drum; a charging roller for electrically charging the electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum; an input electrode extending along a longitudinal direction of the developing roller; an output electrode extending along a longitudinal direction of the developing roller; a grounding contact for electrically grounding the photosensitive drum to a main assembly of the apparatus when the cartridge is mounted to the main assembly of the apparatus, the grounding contact being exposed at an end surface of a cartridge frame provided at one longitudinal end of the photosensitive drum and being disposed across an axis of the photosensitive drum; a charging bias contact for receiving a charging bias voltage to be applied to the charging roller from the main assembly of the apparatus when the cartridge is mounted to the main assembly of the apparatus, the charging bias contact being exposed and facing downwardly adjacent one longitudinal end of the photosensitive drum when the cartridge is mounted to the main assembly of the apparatus; a developing bias contact for receiving a developing bias to be applied to the developing roller from the main assembly of the apparatus when the cartridge is mounted to the main assembly of the apparatus, the developing bias contact being exposed and facing downwardly adjacent one longitudinal end of the photosensitive drum when the cartridge is mounted to the main assembly of the apparatus, and the developing bias contact being disposed at a side opposite from the charging bias contact with the photosensitive drum interposed therebetween with respect to a direction crossing a longitudinal direction of the photosensitive drum; an input electrical contact for receiving an input bias to be applied to the input electrode from the main assembly of the apparatus when the cartridge is mounted to the main assembly of the apparatus, the input electrical contact being exposed at an end surface of a cartridge frame provided adjacent a longitudinal end of the photosensitive drum; and an output contact for transmitting, to the main assembly of the apparatus, an output produced on the basis of a value corresponding to an electrostatic capacity between the input electrode and the output electrode and an electrostatic capacity between the developing roller and the output electrode to detect in substantially real time the remaining amount of the developer in the cartridge by the main assembly of the apparatus when the cartridge is mounted to the main assembly of the apparatus, the output contact being exposed at an end surface of a cartridge frame provided adjacent a longitudinal end of the photosensitive drum.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.